The invention is in a composition of a solid, hydrosoluble formulation containing glyphosate as the active agent for the destruction and/or control of unwanted vegetation and a process for the manufacture of the composition.
Glyphosate [N-phosphonomethyl)glycine] is generally recognized as a highly-effective and efficient herbicide. It is also known that glyphosate is an organic acid which is relatively insoluble in water. Consequently, glyphosate acid is applied as a hydrosoluble salt.
The formulation and application of glyphosate as an ammonium or isopropyl ammonium salt is widespread (U.S. Pat. No. 3,799,758 and Proc. North Cent. Weed Control Conf., 1971, 26, 64).
The manufacture and application of a hydrosoluble glyphosate formulation containing sodium salt has also been the subject of many publications (e.g. U.S. Pat. No. 4,140,513).
Auxiliary agents and/or components to improve effectiveness have also been added to solid glyphosate salt formulations in the prior art. Commonly used additives are ionic and non-ionic surfactants, biological activating agents, extenders, bonding agents and diluents, anticaking agents, foam inhibitors and thickeners (ER 220902, EP 255760, EP 378985, EP 498145, EP 448538, WO 93/25081, Monsanto Research Disclosure No. 27161 xe2x80x9cNovel Glyphosate acid wetcake powder formulation effective in control of weedsxe2x80x9d).
Commercial liquid glyphosate formulations can easily be diluted in water to the required concentration for application. Their disadvantage is their poor transportability, since these formulations contain more than 50% water.
The alternative is a solid, hydrosoluble formulation in the form of granules, pellets, pastes or spray dried powders. The disadvantage with these solid formulations is the high cost of manufacture since they generally originate as a glyphosate wetcake or slurry which must then, after homogenization of the components, be desiccated at high energy costs.
A further disadvantage for the small-scale user is that he must weigh out partial quantities to treat small areas. This can easily result in dosage errors, with either too much or too little being applied.
The objectives of the present invention are to avoid the aforementioned disadvantages for the small-scale user, to provide a composition for a solid glyphosate salt formulation which is easy to dose, dissolves quickly in water, is inexpensive and is therefore consumer-friendly, as well as a process for its manufacture.
The objectives are obtained by a composition of the invention. The invention accordingly comprises a solid, hydrosoluble composition for horticultural and agricultural use in the destruction and/or control of unwanted vegetation with the herbicidal active agent glyphosate in the form of its salts, containing the following minimum components:
10 to 30 wt.-% of N-(phosphonomethyl)glycine (glyphosate);
12 to 52 wt.-% of alkali or ammonium hydrogencarbonate or carbonate;
10 to 20 wt.-% of citric acid, oxalic acid or adipic acid;
0.5 to 2 wt.-% of hydrosoluble cellulose;
8 to 12 wt.-% of alkyl ether sulphosuccinates, alkyl ether phosphates; ethoxylated fatty amines and/or ethoxylated fatty alcohols;
50 to 60 wt.-% of alkali or ammonium hydrogencarbonate or carbonate; ammonium sulphate, urea;
0.2 to 1 wt.-% of polydimethyl siloxane; and
1 to 5 wt.-% of polyether siloxane.
In a preferred embodiment the composition has a glyphosate content of 18 to 22 wt.-% and about 10 wt.-% of a surfactant of one or more of ether sulphosuccinate, alkyl ether phosphate, ethoxylated fatty amine and/or ethoxylated fatty alcohol.
Sodium, potassium and/or ammonium are used as salt-forming cations.
Alkyl ether sulphosuccinates, alkyl ether phosphates, ethoxylated fatty alcohols and/or ethoxylated fatty amines are used as surfactants. Apart from their surface-active effect, the surfactants used also serve to reinforce the herbicidal effect (biological activating agents). Polyether siloxanes are also used as biological activating agents. Alkali and/or ammonium hydrogencarbonates or carbonates are used in conjunction with the organic acids such as citric acid, oxalic acid or adipic acid and hydrosoluble cellulose to accelerate disintegration, producing carbon dioxide bubbles, while sodium, potassium and/or ammonium hydrogencarbonate or carbonate, urea and alkali and/or ammonium sulphate are used as extenders, bonding agents and/or diluents. Polydimethyl siloxanes are used as foam inhibitors.
It has been discovered that the homogenized components of the formulation could be compressed into stable tablets, and that these tablets effervesced and dissolved clearly in water. The dose and size of the tablet can be adapted to contain the required defined quantity of glyphosate active agent for 5, 10 or 20 litres of spray mixture.
The formulation of this solid material is manufactured in accordance with a particularly preferred feature of the invention by homogenizing components of the formulation and compressing them into an effervescent tablet in a suitable tablet press. A tablet press such as the Korsch EK 4, for instance. would be suitable for weights of 2 to 35 g. The tablet mixture is compressed at a pressure of 70 to 80 newtons. The resulting tablet (e.g. for 10 litres spray mixture) has a weight of 6 to 7 g, a diameter of about 30 mm and a depth of about 6 to 8 mm.